Xerographic image transfer apparatus



Dec. 19, 1961 H. E. CRUMRINE ET AL 3,013,526

XEROGRAPHIC IMAGE TRANSFER APPARATUS 2 Sheets-Sheet 1 Filed June 16,1958 INVENTOR? Herbert E. Crumrlne BY C )uber h Km m m,

a Q m m F0 EOWWMKLEOU A TTORNE Y Dec. 19, 1961 H. E. CRUMRINE ETAL3,013,526

XEROGRAPHIC IMAGE TRANSFER APPARATUS 2 Sheets$heet 2 Filed June 16, 1958INVENTORH ATTORNEY Herbert E.Crumrine B Charles L.Huber v lllll w UnitedStates Patent Patented Dec. 19, 1961 This invention relates in generalto the field of Xerography and particularly to improvements in atransfer apparatus for use in a Xerographic device.

In the art of electrostatic elcctrophotography, otherwise known asxerography, an image of transferable electroscopic material is formed ona surface and transferred to a sheet or web of support material, Inpractice this transfer has been accomplished by an electrostatictransfer step, although it has been recognized that there might also beused contact transfer to moistened paper or to paper carrying a wax orlike soft substance on its surface. The prior methods of transfer havegenerally been satisfactory where xerography is directed towardreproduction of line copy or in other fields where substantially 100%image transfer is not essential; however, it has been found that many ofthese methods accomplish transfer of considerably less than all theelectroscopic material, with consequent inadequacy for the highrequirements of continuous tone xerography.

The purpose of the invention is to provide a pressure transfer apapratusfor use with flat Xerographic plates whereby essentially all of anelectrostatically adhering image on a xerographic plate is transferredto a support material without smearing, smudging or other deformstion.

In the field of xerography an image body is developed on a Xerographicplate, the image body being secured to the xcrographic plate byelectrostatic forces only and within the influence of electrostaticforces the image body can very easily be smeared or smudged. Unlike manytypes of mechanical forces the electrostatic forces binding the imagebody to the xerographic plate are comparatively weak in preventinglateral motion although they are comparatively strong in preventingmotion of the image body away from the xerographic plate surface.

In the case of pressure transfer in a xerographic process, relativelystrong pressures between the transfer member and the image surface mustbe achieved in order to accomplish transfer of the image body from onemember to the other. At the same time there is virtually no forcesecuring the image body against smearing or smudging. The situationfurther becomes complicated by the fact that the image bearing surfaceitself is fragile and easily broken. According to presently employedembodiments of xerography, the xerographic plate consists of amorphousor vitreous selenium coated on a backing material and this selenium,like the glass which it re sembles in appearance, is extremely brittle.Thus, it is necessary to apply a substantial force evenly and withoutexcess. Furthermore, the contact between the transfer member and theimage bearing surface must be achieved without the formation of smallbubbles or zones in which the proper firm contact is not achieved. Thisrequirement. is necessary in order to avoid the production of speckleprints in which the print may give the appearance of freckles throughlocalized improper transfer.

It is, therefore, an object of this invention to provide an imagetransfer apparatus for transfer of Xerographic powder images, theapparatus being simple and compact in use and structure andbciugefficient in operation.

It is another object of the invention to provide a xerographic imagetransfer apparatus for pressure contact transfer of a Xerographic powderimage to a sup port material.

It is a further object of the invention to provide apparatus forbringing a support material into uniform pressurized contact with asurface bearing a transferable xerographic powder image for transferringthe xerographic powder image from said surface to the support material.

It is a still further object of the invention to provide an imagetransfer pressure roller apparatus for use in the transfer station of aXerographic machine.

For a better understanding of the invention as well as other objects andfurther features thereof, reference is had to the following detaileddescription of the invention to be read in connection with theaccompanying drawings, wherein: Y

FIG. 1 is a front elevation view of a preferred embodiment of an imagetransfer pressure roller apparatus, partially broken away to illustratethe various elements of the device.

FIG. 2 is a side elevation of the apparatus, partially broken away toillustrate the various elements of the device.

FIG. 3 is a detail vertical sectional view taken along line 3-3 of FIG.1.

FIG. 4 is a diagrammatic side elevation of the transfer station of axerographic machine with the imagetransfer pressure roller apparatusmounted thereon, and

FIGS. 5 and 6 are diagrammatic side elevations of the pertinent elementsof FIG. 4, illustrating successive stages in the operation of the imagetransfer pressure roller apparatus.

Referring now to FIGURES 1 to 3, inclusive, there is disclosed apreferred pressure transfer roller assembly, generally designated 5, foruse in a preferred image transfer apparatus illustrated in FIGURES 4 to6, inelusive.

The pressure transfer roller assembly 5, in the particular arrangementdisclosed herein, includes a frame 10 resiliently mounted to supportpillarslocated at the transfer station of a Xerographic machine. Theframe 10 consists of a left-hand frame member 11 and a righthand framemember 12 rigidly secured to each other by horizontal tie straps 13 anddiagonal tie straps 14 fastened to the left-hand and right-hand framemembers 11 and 12, respectively, by screw fasteners 15, the lower endsof the diagonal tie straps being positioned by spacer blocks 26. Theleft-hand frame member 11 consists of a left-hand hanger 16 which isbifurcated at its lower end to form a fork 17 into which is pivotallyfastened a lower roller arm 18 by means of a pin 19 and retainerrings20. The right-hand frame member 12 also consists of a right-handhanger 21 also forked at its lower end to receive a lower roller arm 18secured in a similar manner by a pin 19 and retainer rings20. Both theleft-hand and right-hand hangers 16 and 21, respectively, have spacedside members 22, a top member 41,-and a bottom member or leg 42 formingan opening 23 extending transversely of each hanger.

As viewed in FIG. 2, a pair of guides 24 are positioned in the bottom ofthe openings 23 and are secured by machine screws 25. A pair of slidingbearings'or bearing blocks 27 are positioned in the openings 23 of boththe left-hand and right-hand hangers 16 and 21, respectively. Thesliding hearings or bearing blocks 27 are retained in place by guides 24at one end, and at the other end by guide blocks 28 positioned in slots29 formed in side members 22 of each hanger. The sliding bearing orbearings 27 are secured to the guide blocks 28 by means of pivot pins 30which also pivotally secure the lower knuckles 31, the pivot pins 30being locked in position by retainer rings 20. A pair of upper knuckles32 are secured in the openings 23 of the left and right hangers in asimilar manner by a second pair of pivot pins and retainer rings 20. Adouble acting air motor 33 is clevis mounted to the knuckles 31 and 32.The cylinder knuckle 34 on the rear end of the air motor 33 is securedto the upper and lower knuckles 32 and 31, respectively, positioned inthe left-hand hanger 16 by means of pivot pin 35. The piston rod 36 ofthe air motor 33 is threadedly secured to a cylinder rod connector 37and locked in position by retaining screw 38, the cylinder rod connector37 in turn being connected to the upper and lower knuckles 32 and 31,respectively, of right-hand hanger 21 by means of a second pivot pin 35.Essentially the upper knuckles 32, lower knuckles 31 and pivot pins formfirst and second machine toggles in the left-hand hanger 16 andright-hand hanger 21, respectively. Movement of the air motor is limitedby stop screws 39 threaded into each of the stop bars 40 secured to theleft-hand hanger 16 and right-hand hangers 21.

An upper roller assembly 43 and a lower roller assembly or drive roller44, each consisting of a rubber 45 covered tubular element or roller 46secured to stub shafts 47, are rotatably journalled by bearings 48secured to the stub shafts 47; the upper roller assembly 43 beingsecured in sliding bearings 27 by retainer rings 20, while lower driveroller assembly 44 is secured in lower roller arms 18 by retainer rings20. For convenience in assembly, the lower roller arms 18 are pivotallysecured to the left-hand and right-hand hangers by pins 19, but arelocked in operating position by bolts 49 threaded into the bottom memberor leg 42 of the hangers, movement of the lower roller arms beingprevented in one direction by the heads of the bolts 49, and movement inthe other direction being prevented by the nuts 50 secured to bolts 49.

As viewed in FIG. 1, the left-hand stub shaft 47 of the lower driveroller assembly 44 is of sufiicient length to permit the mounting of athrust washer 51 (see FlG. 2) and a driven sprocket 52 on the stub shaftoutboard of the lower roller arm 18, the driven sprocket 52 beingsecured to the stub shaft by a retainer ring 20 and a woodruif key (notshown), in the well known manner.

As previously set forth, frame 10, carrying the roller assemblies andthe air motor, is resiliently mounted to vertical support pillarslocated at the transfer station of the xerographic machine. As shown,the vertical support pillars consist of a pair of rods 55 threaded attheir upper ends; the rods 55 preferably may be an integral part of axerographic image forming machine or optionally may be separatelymounted thereon. The legs 42 of the lefthand and right-hand hangers, 16and 21, respectively, have apertures 57 through which the rods pass,while the mounting tie bars 58, secured to the hangers by cap screws 59,have passages 60 of sufficient diameter for the passage of the rods 55and tube elements 61 described below. Secured to the upper portion ofeach of the rods 55 is a tube element 61 welded to a nut 62 and lockedin position by a second nut 62. Springs 63 are telescoped over the tubeelement 61 and are retained by a second pair of nuts 62.

The springs 63 used to support the assembly provide basic alignment ofroller assemblies 43 and 44 with other rollers in the xerographicapparatus, and they serve the function of positioning the lower rollerassembly 44 sufficiently close to the bottom of a plate carriage as itmoves through the xerographic machine that only a minimum amount oftravel will be required to press it against the bottom of a platecarriage during the transfer operation, and at the same time, toeffectively balance the whole system to require a minimum of energy toso position the roller assemblies. This structure permits limitedvertical movement of the frame member on the rods for reasons explainedin more detail in connection with the operation of the device.

Referring now to FIGURES 4 to 6, inclusive, which illustratediagrammatically a preferred embodiment of the image transfer apparatusof the invention for use in a xerographic machine, the air motor 33 ofthe pressure transfer roller assembly 5 is supplied with compressedaeriform fluid by compressor 64 or other source of compressed aeriformfluid, connected to one opening of a; solenoid-operated, four-way valve65. The second and third openings of the solenoid-operated four-wayvalve 65 are connected by flexible conduits 66 to opposite ends of airmotor 33, the fourth opening of the valve being connected to an exhaustconduit 56. Operation of the solenoid-operated four-way valve 65 iscontrolled by a microswitch 87 activated by a cam follower 88 operatingon cam 89 connected to plate carriage or carrier block 68.

As previously set forth, the pressure transfer roller assembly 5 islocated at the transfer station of the xerographic machine (not shown).A xerographic powder image bearing member in the form of anelectrophotographic or xerographic plate 67 including a photoconductivelayer on a conductive backing is mounted on a carrier block or platecarriage 68. The plate carriage 68 with the xerographic plate 67 mountedthereon is supported and moved through the transfer station by means ofcarriage drive rollers 69 and 70, similar to other carriage driverollers throughout the xerographic machine, and the lower rollerassembly 44 of the pressure transfer roller assembly 5, rollers 71merely acting as guide rollers.

For reasons which will be apparent hereinafter, it is' desirable to havethe plate carriage 68 and xerographie' plate 67 propelled solely bymeans of the lower roller assembly 44 as they pass through the pressuretransfer roller assembly 5. To accomplish this, the driven sprocket 52of the lower roller assembly 44 is connected by chain drive 72 to thefirst of two sprockets 52 mounted on shaft 73, the second sprocket beingdriven by a second chain drive 72 from a motor 74, this arrangementproviding a positive drive for lower roller assembly 44.

Since the movement of carriage drive rollers 69 and 70, when either oneis in contact with the plate carriage 68, at the same time that thecarriage is in contact with the lower roller assembly, must notpredominate over the movement of the lower drive roller assembly 44, thecarriage drive rollers 69 and 70 are driven by suitable torqueresponsive devices. Although a number of different torque responsivedevices may be used, as, for example, torque motors or over-runningclutches, in the embodiment disclosed, over-running clutches are used.

As shown, the carriage drive rollers 69 and 70 are rotatably mounted onshafts 75 and 76, respectively, and are driven by clutches 77 secured tothe shafts for rotation therewith. The clutches 77 are of the well knownover-running type, commonly referred to as over-running clutchescommercially available, for example, from the Pormsprag Company of VanDyke, Michigan. By the use of the over-running clutches 77 to drive thecarriage drive rollers 69 and 70, these rollers are free-wheelingrelative to the clutches; that is, an over-running clutch allows adriven member to run at greater speed than its driving member. This istrue even when the driving memher is stopped, reversed or running atslower speed in relation to the driven member.

Each of the shafts 75 is driven by a motor 74 connected by means of asprocket 79 mounted thereon and chain drive 78 to the first of twosprockets 79 attached to shaft 75. The second sprocket 79 on shaft 75 isthe driving sprocket used to transmit power to shaft 76, the units beingconnected by a second chain drive 78 connected to a sprocket 79,attached to shaft 76.

It is apparent that sprockets 52 and 79 are either driving or drivensprockets, depending on their function as described above.

To provide a support material to which the develoyed images from axerographic plate may be transferred, a supply roller or reel 81carrying a roll or web of support material 82 is rotatably mounted onfixed spindle 83, rotation of the supply roller or reel 81 beinggoverned by an over-running clutch 77 of the type previously described.The support material 82 is threaded around upper roller assembly 43 andonto take-up roller or reel 84 rotatably mounted on spindle 85 anddriven by an over-running clutch 77 secured to the spindle 85. A powersource, such as motor 74, is connected by driven and driving sprockets79 secured to the spindle 85 and motor 74,

respectively, and chain drive 78 for applying torque to the take-uproller or reel 84 via the over-running clutch 77 mounted on spindle 85.With the take-up roller drive motor 74 operating, the over-runningclutches 77 for both the take-up roller 84 and the supply roller 81 areadjusted so that balanced tension exists on the web of support material82 to prevent movement of the support material by take-up roller drivemotor 74. As long as the forces acting on the supply roller 81 and thetake-up roller 84 are balanced, the support material will not move.

The sequence of operation of the xerographic transfer apparatus of theinvention is shown in FIGURES 4 to 6, inclusive, all of the motors 74being energized through suitable electrical circuits (not shown). Thepressure transfer roller assembly 5 is shown in FIG. 4 in its normalposition, it being apparent that this device would be supported bysprings 63 as shown in FIG. 1. In this position the upper rollerassembly 43 and the lower lower assembly 44 are separated due to thepiston rod 36 being retracted, compressed aeriform fluid being suppliedto the front end or piston rod end of air motor 33 from air compressor64 through the solenoid-operated four-way valve 65, while the rear endof the air motor 33 is connected by means of the valve to exhaustconduit 56. In this position the lower roller assembly 44 is positionedslightly lower than plate carriage rollers 69 and 70. The movement ofthe plate carriage 68 in the device illustrated is from right to left asseen in FIGURES 4 to 6, inclusive, movement of the plate carriage 68 tothe pressure transfer roller assembly 5 being controlled by the drivencarriage drive rollers 69 and 70 on the right-hand side of the machineas shown. As the carrier block 68 is advanced (see FIG. 5),solenoid-operated four-way valve 65 is energized, as by microswitch 87activated by cam 89 through cam follower 88, whereby the compressor 64is connected to the rear end of the air motor 33 and the front end ofthe air motor is connected to exhaust conduit 56. Since the forcesacting on the cylinder and piston of the air motor are equal andopposite, the forces acting through the machine toggles on the bearingblocks 27 is equal, causing them to move downward carrying the upperroller assembly 43 into contact with the xerographic plate 67 on platecarriage 68 as illustrated in FIGURE 5. As the power stroke continues,further movement of the upper roller assembly 43 is limited by platecarrier 68 still supported by the right-hand drive rollers 69 and 70,and guide rollers 71, so that the frame 10, itself, is forced to moveupward bringing the lower roller assembly 44 into firm contact with thebottom of the plate carriage 68, as illustrated in FIGURE. 6. Thelatter-described movement of the frame is permitted by the resilientmounting means previously described in connection with FIGURES l and 2.

By the use of a compressor or other source of compressed aeriform fluidof sufficient capacity to rapidly activate the piston of the air motor,the time interval between the successive stages shown in FIGURES 5 and 6is negligible.

As the plate carriage 68 is clamped between the upper roller assembly 43and lower roller assembly 44, the lower roller assembly 44 takes overcontrol of the movement of the plate carriage 68 from carriage driverollers 69 and 70. This is due to the fact that in this stage ofoperation the positively driven lower roller assembly 44 is in forcedcontact with the plate carriage while the carriage drive rollers 69 and70 are free-wheeling relative to their contact between the Xerographicplate and the upper roller assembly is sufiicient to overcome thebalanced tension and cause movement of the support material in thedirection of the solid arrow shown in FIGURE.. 6.

In passing between the roller assemblies, the surface of theelectrophotograhic plate meets the support material in pressure contactwhereby the support material picks up and holds any xerographic powderimage or the like on the surface of the electrophotographic plate.

When the support material is stripped from this plate, as

it passes from the upper roller assembly, it carries such image orpowder material in its direct configuration, the image or powdermaterial being permanently bonded to the support material by an imagefixing apparatus 86-, such as disciosed in Carlson Patent 2,624,652.

Since the support material does not move except when in direct contactwith the electrophotographic plate, and then only as a result of themovement of this plate between the roller assemblies, the supportmaterial does not move relative to the plate along the line of transfercontact thereby eliminating any smearing or smudging of the xeropraphicpowder image. The line of transfer contact referred to above is the lineor" contact which the support material, guided by the upper rollerassembly, makes with the electrophotographic plate.

As the plate carriage 68 moves through the pressure transfer rollerassembly 5, the cam follower 8 8 will drop off the cam 89 at the end ofthe plate carriage, thereby opening microswitch 87 with the resultantpositioning of the valve element of solenoid-operated four-way valve 65to permit compressed aeriform fluid to retract the piston of air motor33. As this happens the upper and lower roller assemblies 43 and 44,respectively, move away from the plate carriage 68 and the movementthereafter of the plate carriage away from these roller assemblies iscontrolled by the left-hand (as seen in FIGURE 4) carriagedrive rollers69 and 70.

The support material used may be an adhesive support material, such asdisclosed in Mayo et al. Patent 2,661,- 289, or a normally non-adhesivesupport material such as disclosed in copending applications Serial No.499,784, filed April 7, 1955, and now Patent No. 2,855,324, and SerialNo. 527,354, filed August 9, 1955, and now Patent No. 2,886,464. Thepressure capacity of the compressor and the size of the air cylindershould be properly correlated to force the rollers against thexerographic plate with sufficient force to eifect transfer of thexerographic powder image to the particular support material used.

In regard to FIGURES 4 to 6, inclusive, it is apparent that the variouselements illustrated would be either journaled where necessary orotherwise operatively connected to the structural support elements (notshown) of a xerographic machine in the well-known manner. The structuralsupport elements have been omitted from the drawings since they form nopart of the subject invention and since their inclusion in the drawingswould only detract from the diagrammatic presentation of the essentialelements of the device necessary for a complete disclosure of theinvention.

The speed of passage of the xerographic plate through the mechanism mayvary over a wide range, merely being slow enough to obtain satisfactoryand uniform contact with the particular support material used. Whenoperated under these conditions and with these materials, the mechanismwill yield transfers of substantially of the original image material,whereby the full, accurate I reproduction qualities of the xerographicprocess may be realized.

What is claimed is:

1. An image transfer pressure roller apparatus for use in a Xerographicdevice wherein a flat, xerographic plate, having a Xerographic powderimage thereon is mounted on a plate holder for movement through thetransfer station of the Xerographic device, the transfer apparatusincluding a frame means having two parallel spaced frame members movablysupported on the xerographic device, bearing blocks movably mounted ineach of said frame members, an upper roller assembly journaled in saidbearing blocks for movement with said bearing blocks, a lower driveroller assembly journaled in said frame members in parallel spacedrelationship to said upper roller assembly, bearing block moving meansconnected to said frame members and to said bearing blocks for movingsaid bearing blocks and therefore said upper roller assembly relative tosaid lower drive roller assembly and for moving said frame members andtherefore said lower drive roller assembly relative to said upper rollerassembly, said roller assemblies being movable from a position in whichsaid roller assemblies are in spaced apart relation to receive axerographic plate to a position wherein said roller assemblies areadapted to support a xerographic plate in pressure contact therebetween,and drive means connected to said lower drive roller assembly fordriving said lower drive roller assembly, said roller assemblies thusbeing adapted to receive a fiat xerographic plate and to advance suchmember in pressure contact therebetween.

2. A transfer apparatus for transferring a xerographic powder image froma xerographic powder image bearing member to a support material,including a structural support element, a pair of support pillarsmounted on said structural support element, spring-tensioned mountingmeans positioned on each of said support pillars, a frame means havingtwo parallel spaced frame members movably mounted on said supportpillars and supported by said spring-tensioned mounting means, bearingblocks movably mounted in each of said frame members, a first rollerassembly journaled in said bearing blocks for movement with said bearingblocks, a second roller assembly journaled in said frame members inparallel spaced relationship to said first roller assembly, bearingblock moving means connected to said bearing blocks and to said framemembers for moving said bearing blocks and therefore said first rollerassembly relative to said second roller assembly and for moving saidframe members and therefore said second roller assembly relative to saidfirst roller assembly from a position in which said roller assembliesare in spaced apart relation to receive a xerographic powder imagebearing member to a position wherein said roller assemblies are adaptedto support a Xerographic powder image bearing member in pressure contacttherebetween, drive means connected to said second roller assembly fordriving said second roller assembly, a support material transport meansconnected to said structural support element, said support materialtransport means adapted to hold a supply of support material in tensionaround said first roller assembly, said roller assemblies thus beingadapted to receive a xerographic powder image bearing member and topropel such member in pressure contact with a support materialtherebetween, the forced contact of the xerographic powder image bearingmember with the support material causing movement of the supportmaterial.

3. A transfer apparatus for transferring a xerographic powder image froma xerographic powder image bearing member to a support material,including a support element, a pair of support rods mounted verticallyon said support element, spriug-tensioned mounting means connected toeach of said support rods, a frame means hav ing two parallel spacedframe members movably mounted on said support rods and supported by saidspringtensioned mounting means, bearing blocks movably mounted in eachof said frame members, a first roller assembly journaled in said bearingblocks, a second roller assembly journaled in said frame members inparallel spaced relation to said first roller assembly, a pair of togglemeans each connected at one end to one of said bearing blocks, and atits other end to the frame members in which the bearing block ismounted, power means connected to actuate said toggle means for movingsaid first roller assembly relative to said second roller as sembly andfor moving said frame members and therefore said second roller assemblyrelative to said first roller assembly from a position in which saidroller assemblies are in spaced apart relation to receive a xerographicpowder image bearing member to a position wherein said roller assembliesare adapted to support a ,Xerographic powder image bearing member inpressure contact therebetween, drive means connected to said secondroller assembly for rotating said second roller assembly, and a yieldingtorque-responsive support material transport means operatively connectedto said support element for supplying a web of support material incooperation with said first roller assembly in contact with axerographic powder image bearing member.

References Cited in the file of this patent UNITED STATES PATENTS,606,853 Reese et al Aug. 12, 1952 2,624,652 Carlson Jan. 6, 19532,818,904 Ambrose Jan. 7, 1958 2,820,716 Harmon et al. Jan. 21, 19582,843,499 Andrus July 15, 1958

